Aims. The aim of the transgenic component of is to produce mice that carry single nucleotide polymorphisms (SNPs) identified in other projects of this center that correlate with hypertension and increased vascular resistance phenotypes. Such transgenic mice will be produced using bacterial artificial chromosomes (BACs) containing the candidate gene of interest. This BAC will code for either the wild-type sequence or the SNP associated with the human phenotype. The BAC containing the SNP will be produced by site-directed mutagenesis using homologous recombination to bacteria. To isolate the phenotypic effects of the wild- type and SNP-associated gene, we will take advantage of already existing knock-out mice for several of the candidate genes we wish to study to completely eliminate the mouse gene. We plan to make five wild-type and modified BAC transgenic mice per year. If we evaluate one locus, that will allow us to make one wild-type and four SNPs for one locus in one year. The aim of the phenotyping component of is to characterize vascular and cardiac phenotypes of these mice to assess the functional importance of SNPs identified in human expressed in mice. Studies on vascular responses at baseline and dose-responses to administered vasoactive agents will involve hemodynamic studies on the systemic or pulmonary vascular beds; regional circulations can also be evaluated by fluorescent microsphere techniques, if required. Evaluation of morphologic and functional cardiac phenotypes using transthoracic echocardiography and microangiography also will be available. These studies will allow us to "humanize" the mouse for the particular locus of interest, and assess the phenotypic effects of wild-type or SNP- associated gene function in a model organism. In this way, we should be able to directly test whether the SNP identified in the human population does in fact have phenotypic consequences in a model organism.